Now, FWIW, I'm building another search engine. Instead of 20 engineers we have just me. Instead of 4 years, we're going to do it in one. While I have no interest in going up against google (different plans entirely) the radical change in leverage you get with open source and PAAS or IAAS, combined with Google's having taken their eye off the ball and run off to chase Facebook down a blind alley, means that something like DuckDuckGo actually could take real share away... maybe. (%1 of google's volume would be "Real share" right?)
[1] Oracle did have full text search but did not have the performance or per-machine-efficiency we needed, so it cost us a lot, and it was a constant fight to get it to do the kind of queries our relevancy algos required. we had a constant stream of consultants in from oracle HQ, and in the end dumped it and wrote our own db from scratch in about 4 months.